The invention relates to a vehicle occupant restraint device comprising an inflatable knee airbag. The invention further relates to a method for protecting a vehicle occupant.
The inflating and exhaust behavior of airbags is tested with crash test dummies during impact tests. Crash test dummies are life-size dolls imitating the human body. In order to duly consider the different anatomic conditions of real persons during simulations, the tests are usually carried out with three different dummies: The “50 percent male” having a body height of 175 cm and a weight of 78 kg is supposed to correspond in general to a “normally” sized vehicle occupant, the “95 percent male” having a body height of 188 cm and a weight of 101 kg is supposed to correspond to a tall vehicle occupant and the “5 percent female” having a body height of 152 cm and a weight of 54 kg is to correspond to a short vehicle occupant. Due to the different constitution, in the crash tests the normal seating positions of the different dummies and the distances of particular body parts from the surrounding vehicle components vary accordingly.
In modern vehicle safety systems comprising airbag modules it is endeavored to adapt the safety system increasingly individually to different parameters of a crash situation. A known and advantageous possibility is the use of tensile means such as e.g. tethers by the release of which exhaust orifices of the airbag are opened or closed. Moreover, by those tensile means also the airbag geometry can be influenced and/or an additional airbag volume can be released. For this purpose, activating units are known, e.g. under the acronym “TAU” (tether-activation-unit), by which the release of tethers can be actively controlled. Airbag modules including said activating units are known, for example, from DE 10 2008 028 921 A1 or DE 10 2009 005 771 A1.